97 boxster not hot starting

[Bow.........]

I have a 97 boxster. about half a year ago the car started to stall when it got above optimal operating temp. (About 3/4 in between 180 and the next notch on the temp gauge). This happened both on the highways (only with high traffic would it get this hot) and in the city. Sense then it has also started to stall (not all the time) at idle if I am at a stop light at that temp. The revs will bounce with each bounce dropping in rpm. I found that pressing the accelerator helped If I could catch it in time. I manage to plan to keep this from happening just by not letting the car get too warm, but more recently, the car has had problems starting when as warm as 180. The starter cranks but the motor does not turn over. I'll let it sit and once it is cooled down it has no problem starting. I haven't been able to find a nother post with these problems and I would really appreciate any help. I have narrowed it  down to either needing to replace the fuel pump, crank shaft position sensor. 

Edited May 12, 2018 by Bow.........

[JFP in PA]

I would check the fuel system for correct pressure and delivery rates, and also check the CPS.

[Bow.........]

For the first time, today the vehical had stalled while at optimum temp (180) while doing some tests on the car. When this happened I heard something blowing out pressure as it stalled. does anyone know if this could have been caused by a failing fuel pressure regulator. And would varying engine teps cause this due to engine compartment temp rising? Should I test The vacuum lines as well? Any input is greatly appreciated 

[wizard]

Just on the off chance that it's not fuel related, have you checked your coolant level? You might also open your burp valve to ensure that there's no air trapped in the system.

 

Do you have the latest coolant reservoir cap - part number ending in 'O4'?

 

 

[mikefocke]

When it doesn't start does the tachometer bounce at all when the key is turned?

 

Are your radiators clear of debris?

[Bow.........]

No the tack doesn't bounce or move at all, so I do not believe the issue to be the cps 

[ttocs]

Have you addressed any of the suggestions above related to the cooling system?

[mikefocke]

1. CPS sensors are notorious for failing at high temperatures, cooling off and working again until .....

2. The tach not bouncing is another sign of a probable CPS sensor failure. Several of the forums have folks who posted the diagnostic methods of checking voltages on the CPS.